<template>
  <div class="spec-preview">
    <img :src="skuImageList[defaultIndex]?.imgUrl" />
    <div class="event" @mousemove="mousemove"></div>
    <div class="big">
      <img :src="skuImageList[defaultIndex]?.imgUrl" ref="bigImgEle"/>
    </div>
    <div class="mask" ref="maskEle"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuImageList"],
  mounted() {
    this.$bus.$on("getZoomIndex",(index)=>{
          this.defaultIndex=index;
    });
  },
  data() {
    return {
      defaultIndex: 0,
    };
  },
  methods: {
    mousemove(e) {
      //得到鼠标到外层元素边缘的距离
      const mouseToOut = {
        left: e.offsetX,
        top: e.offsetY,
      };
       //计算蒙版的位置
       const maskLoaction= {
        x:mouseToOut.left-this.$refs.maskEle.offsetWidth/2,
        y:mouseToOut.top-this.$refs.maskEle.offsetHeight/2,
        
       };
       //处理临界值
       if(maskLoaction.x<0){
        maskLoaction.x=0;

       }else if (
       maskLoaction.x>=
       e.target.clientWidth-this.$refs.maskEle.offsetWidth
       ){
       maskLoaction.x = e.target.clientWidth - this.$refs.maskEle.offsetWidth;
       }
       
       if(maskLoaction.y<0){
        maskLoaction.y=0;

       }else if (
       maskLoaction.y>=
       e.target.clientHeight-this.$refs.maskEle.offsetHeight
       ){
       maskLoaction.y = e.target.clientHeight - this.$refs.maskEle.offsetHeight;
       }
       //赋值
       this.$refs.maskEle.style.top=maskLoaction.y+"px"
       this.$refs.maskEle.style.left=maskLoaction.x+"px"
       //控制大图位移
       this.$refs.bigImgEle.style.left=-2*maskLoaction.x+"px";
       this.$refs.bigImgEle.style.top=-2*maskLoaction.y+"px";
       

       


      
    }
  }
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>